This invention concerns a device for hyperthermia and, more specifically, it relates to a high-frequency heating electrodes device, in particular, a high-frequency electrodes device for medical use which can be applied to the hyperthermia therapy of tumors or cancers.
This invention further relates to an improvement of at least one of paired electrodes for use in the high-frequency device for hyperthermia.
High-frequency hyperthermia therapy has been known in which the high-frequency energy, typically radio-frequency energy, is applied to a lesion portion of a patient in the form of heat for therapy where the nature of the cancer that the cancer cells are less resistant to heat or elevated temperature than normal cells is utilized.
The hyperthermia therapy has been carried out in the conventional high-frequency heating technique, for instance as shown in FIGS. 1 and 2, by disposing a pair of plate-like electrodes 4, 5 on opposed surface positions of a living body 1 so that a region 3 including a part 2 to be heated of the living body 1 may be situated between the two plate-like electrodes 4 and 5, and by supplying a high-frequency current from a high-frequency power supply 6 through the electrodes, 4, 5 disposed on the sides of the belly and the back.
However, the high-frequency currents pass substantially in parallel throughout the region 3 between the opposing electrodes 4, 5 according to this conventional technique, which results in the undesirable heating of portions other than the part or portion 2 intended to be heated. Moreover, there is fear that a subcutaneous fat layer 7 may be heated more strongly than the intended portion 2 due to the differences in the electric properties or factors such as the electric conductivity and the dielectric constant between the subcutaneous fat layer 7 and the tissue of the tract organ including the lesion part 2. It has thus been difficult to heat or warm the lesion part 2 at the deep inside of the living body to a temperature desired for the hyperthermia therapy because of the patient's complaint about heat and the risk of scalding of the epidermis tissue.
As one of the techniques for overcoming the foregoing problems, it has been attempted to dispose a pointed electrically conductive member such as a metallic needle at the aimed or intended part to be heated for locally applying the heat thereto by concentrating the electric field between the opposed plate-like electrodes on the aimed part around the metallic needle. Although this technique is effective for concentrating the electric field on the aimed part, it is not always preferred because surgical skills are required for inserting and extracting the metallic needle or the like, and because much pain is given to the patient for the technique is essentially invasive.